Broadcasting receiver, broadcasting identification method, broadcasting identification program, and recording medium therefor

ABSTRACT

While sequentially changing the selected channel, a digital broadcast judgment part collects level value V W  of a signal extracted on a wide band, a bandwidth suitable for reproduction of an analog broadcast, reported from a reproduction processing unit as the level detection result, and a signal level value V N  extracted on a narrow bandwidth of about ΔF for which, in an IBOC system, it is likely that neither a digital nor analog broadcast component is present. This digital broadcast judgment part searches for a channel upon which hybrid broadcasting performed by sequentially judging, for three successive channels, whether the first and second adjacent channel conditions, and a central channel condition are satisfied, only on the basis of the signal level values V W  and V N . Accordingly, when receiving a radio broadcast according to the IBOC system, it is possible to decide promptly whether or not a digital broadcast is included therein.

TECHNICAL FIELD

The present invention relates to a broadcast receiving device, abroadcast identification method, a broadcast identification program, anda recording medium upon which such the broadcast identification programis recorded.

BACKGROUND ART

From the past, radio receiving device which receive broadcast radiowaves and reproduce their broadcast contents have been widespread.Although traditionally, as such radio broadcasts, analog broadcasts havebeen employed, the use of digital broadcasts has advanced in recentyears.

One digital broadcasting system is the IBOC (In-Band On-Channel) system,which is employed in the USA. In this IBOC system, hybrid broadcastingis employed, in which a digital broadcast can be appended to an analogbroadcast. By doing this, it becomes possible to enhance the soundquality as a result of HD (High Definition) radio broadcasting in whichdigital broadcasting is employed. In a hybrid broadcast according tothis IBOC system, the digital broadcast carrier wave is located in thefrequency bands adjacent to the analog broadcast carrier wave, on bothits sides.

Now, it is not the case that all broadcasting stations perform hybridbroadcasting. In other words, although hybrid broadcasting may beperformed by some broadcasting stations, other broadcasting stations mayonly perform analog broadcasting. In such a case, for radio broadcastingby the amplitude modulation method, a technique has been proposed ofperforming auto seek in order to find a broadcasting station which isperforming hybrid broadcasting (refer to Patent Document #1, hereinaftertermed the “prior art example”).

In this prior art example, during auto seek, the system starts from anauto seek start frequency, and, as tuning frequencies, the tuner issequentially set to frequencies spaced apart by some predeterminedfrequency interval. And, each time a tuning frequency is set, theelectric field intensity of the radio wave which corresponds to thattuning frequency is detected by detecting signal power having thebandwidth of a normal analog broadcast.

Next, from the result of detection of the electric field intensity, ajudgment is made as to whether a broadcast wave corresponding to eitheran analog broadcast or a hybrid broadcast, either of which have a chosenfrequency by dialing, is being received. If the result of this judgmentis negative, then no decision is made as to whether or not this is ahybrid broadcast, but instead the tuning frequency is changed over.

On the other hand, if the result of this judgment as to whether abroadcast wave corresponding to either an analog broadcast or a hybridbroadcast is being received, either of which have a chosen frequency bydialing, is affirmative, then the received signal is digitally analyzed,and a judgment is made as to whether or not it includes a digitalbroadcast. As a result, auto seeking for a hybrid broadcast isimplemented more rapidly than in the case of, each time a tuningfrequency is set, digitally analyzing the received signal and making ajudgment as to whether or not a digital broadcast is included.

-   Patent Document #1: Japanese Laid-Open Patent Publication    2005-12593.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

With this technique according to the prior art example, when autoseeking for a digital broadcast, it is possible to change over thetuning frequency rapidly from the result of detection of the electricfield intensity, since, if the result of the judgment as to whether abroadcast wave corresponding to either an analog broadcast or a hybridbroadcast is being received corresponding to that tuning frequency isnegative, then it is possible to manage without performing digitalanalysis of the received signal. However, if the result of that judgmentis affirmative, then it is necessary to perform digital analysis of thereceived signal, for which a time period of around one second isrequired.

Due to this, a technique is very much desired for being able to decidewhether or not a digital broadcast is included according to the IBOCsystem promptly, even if the result of the above judgment isaffirmative. The provision of a response to this demand is one of theproblems which the present invention is intended to solve.

Thus, the present invention has been conceived in consideration of thecircumstances described above, and its objective is to provide abroadcast receiving device and a broadcast identification method which,upon the reception of a radio broadcast according to the IBOC system,are capable of promptly deciding whether or not a digital broadcast isincluded therein.

Means for Solving the Problems

According to a first aspect thereof, the present invention is abroadcast receiving device, characterized by comprising: a tuner partconfigures to, according to a tuning command, converts a signal in asignal from a signal source, on a frequency band corresponding to saidtuning command, to an intermediate frequency signal, which is a signalon an intermediate frequency band whose center frequency is apredetermined frequency; a first filter part configures to, if saidpredetermined frequency corresponds to a frequency of a carrier wave ofan analog radio broadcast wave according to the amplitude modulationmethod, takes said predetermined frequency as a center frequency, andselects from said intermediate frequency signal and passes through asignal on a first frequency band which is appropriate for reproducingbroadcast contents from said analog radio broadcast wave; a secondfilter part configures to takes said predetermined frequency as a centerfrequency, and selects from said intermediate frequency signal andpasses through a signal on a second frequency band whose bandwidth isnarrower than said first frequency band; a first detection partconfigures to detects a first power level, which is the power level ofthe signal passed through said first filter part; a second detectionpart configures to detects a second power level, which is the powerlevel of the signal passed through said second filter means; a tuningcontrol part configures to issues said tuning command to said tunermeans; and a judgment_part configures to, on the basis of said firstpower level and said second power level obtained corresponding to atuning command in which a specific channel is designated, and said firstpower level and said second power level obtained corresponding to atuning command in which at least one adjacent channel to said specificchannel is designated, makes a judgment as to whether or not a digitalradio broadcast which takes the center frequency of said specificchannel as its center frequency is being performed according to thein-band-on-channel method.

And, according to a second aspect thereof, the present invention is abroadcast identification method, characterized by comprising: a tuningprocess of, according to a tuning command, converting a signal in asignal from a signal source, on a frequency band corresponding to saidtuning command, to an intermediate frequency signal, which is a signalon an intermediate frequency band whose center frequency is apredetermined frequency; a first detection process of, if saidpredetermined frequency corresponds to a frequency of a carrier wave ofan analog radio broadcast wave according to the amplitude modulationmethod, taking said predetermined frequency as a center frequency,extracting from said intermediate frequency signal a signal on a firstfrequency band which is appropriate for reproducing broadcast contentsfrom said analog radio broadcast wave, and detecting the power level ofthis extracted signal; a second detection process of taking saidpredetermined frequency as a center frequency, extracting from saidintermediate frequency signal a signal on a second frequency band whosebandwidth is narrower than said first frequency band, and detecting thepower level of this extracted signal; and a judgment process of, on thebasis of the result of detection by said first detection process and theresult of detection by said second detection process when a specificchannel has been designated by said tuning command, and the result ofdetection by said first detection process and the result of detection bysaid second detection process when at least one adjacent channel to saidspecific channel has been designated by said tuning command, making ajudgment as to whether or not a digital radio broadcast which takes thecenter frequency of said specific channel as its center frequency isbeing performed according to the in-band-on-channel method.

According to a third aspect thereof, the present invention is abroadcast identification program, characterized in that it causes acalculation means to execute a broadcast identification method accordingto the present invention.

According to a fourth aspect thereof, the present invention is arecording medium, characterized in that a broadcast identificationprogram according to the present invention is recorded thereupon, andcan be read in by a calculation means.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram schematically showing the structure of abroadcast receiving device according to the first embodiment of thepresent invention;

FIG. 2A is the first figure for explanation of a broadcast wavefrequency distribution supposed by the device of FIG. 1;

FIG. 2B is the second figure for explanation of the broadcast wavefrequency distribution supposed by the device of FIG. 1;

FIG. 3 is a block diagram showing the structure of a tuner unit of FIG.1;

FIG. 4 is the block diagram showing the structure of a reproductionprocessing unit of FIG. 1;

FIG. 5 is the block diagram showing the structure of an analog broadcastprocessing part of FIG. 4;

FIG. 6 is the block diagram showing the structure of a digital broadcastprocessing part of FIG. 4;

FIG. 7 is the block diagram showing the structure of a control unit ofFIG. 1;

FIG. 8 is a flow chart for explanation of seek processing for a hybridbroadcast by the device of FIG. 1;

FIG. 9 is the flow chart for explanation of processing in FIG. 8 forjudging upon the first adjacent channel condition;

FIG. 10 is the flow chart for explanation of processing in FIG. 8 fornext channel tuning processing;

FIG. 11 is the flow chart for explanation of processing in FIG. 8 forjudging upon a central channel condition;

FIG. 12 is the flow chart for explanation of processing in FIG. 8 forjudging upon a second adjacent channel condition;

FIG. 13 is the flow chart for explanation of hybrid broadcast all rangescanning processing performed by the device of FIG. 1;

FIG. 14 is the block diagram schematically showing the structure of abroadcast receiving device according to the second embodiment of thepresent invention;

FIG. 15 is the block diagram showing the structure of a reproductionprocessing unit of FIG. 14; and

FIG. 16 is the block diagram showing the structure of an analogbroadcast processing part of FIG. 15.

BEST MODE FOR CARRYING OUT THE INVENTION

In the following, embodiments of the present invention will be explainedwith reference to the appended drawings. It should be understood that,in the following explanation, the same reference symbols are attached toelements which are the same or equivalent, and duplicated explanation isomitted.

The First Embodiment

First, the first embodiment of the present invention will be explainedwith reference to FIGS. 1 through 13.

<Structure>

FIG. 1 is a block diagram schematically showing the structure of abroadcast receiving device 100A according to the first embodiment. Itshould be understood that this broadcast receiving device 100A is abroadcast receiving device which is capable of receiving and reproducingan amplitude modulated radio broadcast according to the IBOC system.

As shown in FIG. 1, this broadcast receiving device 100A comprises anantenna 110, a control unit 120A, a tuner unit 130 which serves as atuner means, and an analog-digital converter (ADC) 135. Moreover, thebroadcast receiving device 100A comprises a reproduction processing unit140A, a digital-analog converter (DAC) 145, an audio volume adjustmentunit 150, and a power amplifier 155. Yet further, the broadcastreceiving device 100A comprises a speaker 160, an actuation input unit170, and a display unit 180.

The antenna 110 receives broadcast waves transmitted from broadcastingstations. The result of reception by this antenna 110 is outputted tothe tuner unit 130 as a received signal RFS.

Now, the frequency distribution of the signal power of the receivedsignal RFS received by the antenna 110 will be explained. It should beunderstood that it will be supposed that the center frequency f_(j) of aphysical channel (hereinafter also sometimes simply termed a “channel”)which is used for a radio broadcast by the method of amplitudemodulation is set in advance. And it will be supposed that the frequencydifference between the center frequency f_(j) of a specified channel andthe center frequency f_(j−1) or f_(j+1) of an adjacent channel(hereinafter also sometimes termed the “channel interval”) is a constantvalue Δf. It should be understood that, in this embodiment, thefollowing explanation is given in terms of “Δf=10 kHz” being the case.

If a hybrid broadcast including both an analog broadcast and a digitalbroadcast which take the frequency f_(p) as center frequency is beingperformed, then, as shown in FIG. 2A, the analog broadcast componentABS_(p) is included in the frequency range (f_(p)−5 kHz)˜(f_(p)+5 kHz).Moreover, the third upper sideband component DTU_(p) of the digitalbroadcast is included in the frequency range f_(p)˜(f_(p)+5 kHz), whilethe third lower sideband component DTL_(p) of the digital broadcast isincluded in the frequency range (f_(p)−5 kHz)˜f_(p).

Furthermore, the second upper sideband component DSU_(p) of the digitalbroadcast is included in the frequency range (f_(p)+5 kHz)˜(f_(p)+10kHz), while the second lower sideband component DSL_(p) of the digitalbroadcast is included in the frequency range (f_(p)−10 kHz)˜(f_(p)−5kHz). Yet further, the first upper sideband component DPU_(p) of thedigital broadcast is included in the frequency range (f_(p)+10kHz)˜(f_(p)+15 kHz), while the first lower sideband component DPL_(p) ofthe digital broadcast is included in the frequency range (f_(p)−15kHz)˜(f_(p)−10 kHz).

In other words, with a hybrid broadcast which includes both an analogbroadcast and a digital broadcast, it is arranged to utilize thefrequency bands for three channels: one channel for the center frequencyf_(p), and the two channels adjacent thereto for the upper and lowersidebands. In the following, among these three channels which areemployed for this type of hybrid broadcast shown in FIG. 2A, the centerchannel will be termed the “central channel”, while the two channelsadjacent to this central channel will be termed the first adjacentchannel and the second adjacent channel.

It should be understood that, as shown in FIG. 2A, in the case of ahybrid broadcast, a frequency region of frequency width ΔF, in which nocomponent is located, is present between the frequency band of the uppersideband second component DSU_(p) of the digital broadcast and thefrequency band of its upper sideband first component DPU_(p).Furthermore, a frequency region of frequency width ΔF, in which nocomponent is located, is also present between the frequency band of thelower sideband second component DSL_(p) of the digital broadcast and thefrequency band of its lower sideband first component DPL_(p).

If only analog broadcasting is being performed, with the frequency f_(q)being taken as the center frequency, then, as shown in FIG. 2B, theanalog broadcast component ABS_(q) is included within the frequencyrange (f_(q)-5 kHz)˜(f_(q)+5 kHz). Moreover, if analog broadcasting isbeing performed upon an adjacent channel whose center frequency isf_(q−1) or f_(q+1), then an analog broadcast component ABS_(q−1) orABS_(q+1) which uses an adjacent channel as shown by the broken line inFIG. 2B is present. On the other hand, if no such analog broadcasting isbeing performed upon an adjacent channel whose center frequency isf_(q−1) or f_(q+1), then such an analog broadcast component ABS_(q−1) orABS_(q+1) does not exist.

Although this feature is not shown in FIG. 2B, it should be understoodthat it may also be the case that, when analog broadcasting only at thecenter frequency of f_(q) is being performed, in the frequency region ofan adjacent channel, there may be present a signal component of adigital broadcast whose center frequency is a channel adjacent to thatadjacent channel. In this case, if a signal component of a digitalbroadcast is present in a channel region adjacent to the lower sidebandof that channel, then its lower sideband second component DSU_(q−2) isincluded in the frequency range (f_(q)−10 kHz)˜(f_(q)−5 kHz), and itslower sideband first component DPU_(q−2) is included in the frequencyrange (f_(q)−15 kHz)˜(f_(q)−10 kHz). On the other hand, if a signalcomponent of a digital broadcast is present in a channel region adjacentto the upper sideband of that channel, then its upper sideband secondcomponent DSL_(q+2) is included in the frequency range (f_(q)+5kHz)˜(f_(q)+10 kHz), and its upper sideband first component DPL_(q+2) isincluded in the frequency range (f_(q)+10 kHz)˜(f_(q)+15 kHz).

Returning to FIG. 1, the control unit 120A controls the overalloperation of the broadcast receiving device 100A. This control unit 120Awill be described hereinafter.

The tuner unit 130 performs tuning processing according to a tuningcommand CSL from the control unit 120A, and outputs a tuning signal IFShaving a predetermined intermediate frequency to the ADC 135. As shownin FIG. 3, this tuner unit 130 comprises an input filter 211, a highfrequency amplifier (RF-AMP: Radio Frequency Amplifier) 212, and a bandpass filter 213 (hereinafter also sometimes termed an “RF filter”).Moreover, this tuner unit 130 comprises a mixer (mixing device) 214, anintermediate frequency filter 215 (hereinafter also sometimes termed an“IF filter”), and an intermediate frequency amplifier (IF-AMP:Intermediate Frequency Amplifier) 216. Yet further, the tuner unit 130further comprises a local oscillation circuit (OSC) 219.

The input filter 211 is a high pass filter which intercepts lowfrequency components of the received signal RFS from the antenna 110.And the high frequency amplifier 212 amplifies the signal which passesthrough this input filter 211.

The RF filter 213 selectively passes signals of a specified frequencyrange in the signal outputted from the high frequency amplifier 212. Themixer 214 mixes together the signal passed through the RF filter 213 anda local oscillation signal which is supplied by the local oscillationcircuit 219. And, from the signal outputted from the mixer 214, the IFfilter 215 selects and passes through a signal in a predeterminedintermediate frequency range (of frequency width about 40 kHz).

The intermediate frequency amplifier 216 amplifies the signal passedthrough by the IF filter 215. The result of this amplification by theintermediate frequency amplifier 216 is supplied to the ADC 135 as thetuning signal IFS.

The local oscillation circuit 219 includes an oscillator etc., and itsoscillation frequency can be controlled by voltage control or the like.According to the tuning command CSL supplied from the control unit 120A,this local oscillation circuit 219 generates a local oscillation signalof a frequency corresponding to the channel to be tuned to by the tunerunit 130, and supplies this signal to the mixer 214.

Returning to FIG. 1, the ADC 135 receives the tuning signal IFS, whichis an analog signal. And the ADC 135 converts this tuning signal IFSinto a digital signal. The result of this conversion is then sent to thereproduction processing unit 140A as a digital tuning signal IFD.

Under control by the control unit 120A, the reproduction processing unit140A processes the digital tuning signal IFD from the ADC 135, andgenerates a processed broadcast signal BPD. And, as shown in FIG. 4,this reproduction processing unit 140A is provided with an analogbroadcast processing part 220A, a digital broadcast processing part 230,and a combination part 240.

The analog broadcast processing part 220A processes the digital tuningsignal from the ADC 135, and generates a processed analog broadcastsignal ABD. As shown in FIG. 5, this analog broadcast processing part220A comprises a band pass filter part (BPF) 221WA which serves as thefirst filter means, a band pass filter part (BPF) 221NA which serves asthe second filter means, and a switch part 222A. Moreover, this analogbroadcast processing part 220A also comprises a wave detection part 223A(DET) which serves as the first detection means and the second detectionmeans, a noise cancellation part 224A (NC), and an automatic receptioncontrol part 225A (ARC).

The BPF 221WA receives the digital tuning signal IFD from the ADC 135.And, when analog broadcasting is being performed using a channelcorresponding to a tuning command CSL, the BPF 221WA selectively passesthrough signal components in a predetermined frequency range necessaryfor reproduction of that analog broadcast. Here, if the center frequencyin the digital tuning signal IFD of the channel corresponding to thetuning command CSL is taken as F_(j), then the frequency range of thesignal passed through by the BPF 221WA is within the frequency range(F_(j)−5 kHz)˜(F_(j)+5 kHz), and has the first predetermined frequencyrange centered at the frequency F_(j) and sufficiently broader than theabove described frequency width ΔF. The signal passed through the BPF221WA is taken as a signal WBD, and is supplied to the switch part 222A.

It should be understood that this first predetermined frequency range isdetermined in advance on the basis of experiment, simulation,experience, and so on.

The BPF 221NA receives the digital tuning signal IFD from the ADC 135.The BPF 221NA passes through signal components in a second predeterminedfrequency range, whose frequency width is centered at the frequencyF_(j) and is sufficiently narrower than the above described firstpredetermined frequency width. The signal passed through the BPF 221NAis taken as a signal NBD, and is supplied to the switch part 222A.

It should be understood that this second predetermined frequency rangeis also determined in advance on the basis of experiment, simulation,experience, and so on.

At its A terminal, the switch part 222A receives the signal WBD from theBPF 221WA. Moreover, at its B terminal, the switch part 222A receivesthe signal NBD from the BPF 221NA. And, according to the bandwidthselection command BWC from the control unit 120A, the switch part 222Aselects either the signal WBD or the signal NBD, and outputs the signalSBD from its C terminal.

The wave detection unit 223A receives the signal SBD from the switchpart 222A. And the wave detection part 223A performs wave detectionprocessing upon the signal SBD by some predetermined method. The resultof this wave detection is outputted to the noise cancellation part 224Aas a wave detection signal DTD.

It should be understood that the wave detection part 223A is endowedwith a so called S-meter function of detecting the power level of thesignal SBD. The signal power level which it detects by using thisS-meter function is reported to the control unit 120A as a leveldetection result DLD.

The noise cancellation part 224A receives the wave detection signal DTDfrom the wave detection part 223A. And the noise cancellation part 224Aeliminates high frequency noise and so on which is superposed upon thewave detection signal DTD, thus generation a noise cancelled signal NCD.This noise cancelled signal NCD is sent to the automatic receptioncontrol part 225A.

The automatic reception control part 225A receives the noise cancelledsignal NCD from the noise cancellation part 224A. And this automaticreception control part 225A estimates the state of fluctuation of theradio waves on the basis of the noise cancelled signal NCD, and performsauto high cut processing and/or shift muting processing according to theresult of this estimation. The result of this processing by theautomatic reception control part 225A is sent to the combination part240 as the processed analog broadcast signal ABD.

Returning to FIG. 4, the digital broadcast processing part 230 processesthe digital tuning signal IFD from the ADC 135, and generates aprocessed digital broadcast signal DBD. As shown in FIG. 6, this digitalbroadcast processing part 230 comprises an OFDM demodulation part 231and a decoding part 232.

The OFDM demodulation part 231 performs OFDM demodulation processing onthe basis of the digital tuning signal IFD. The result of thisdemodulation by the OFDM demodulation part 231 is sent to the decodingpart 232 as a demodulated signal DMD.

The decoding part 232 receives the demodulated signal DMD from the OFDMdemodulation part 231. And the decoding part 232 performs decoding ofthis demodulated signal DMD. The result of this decoding is sent to thecombination part 240 as the processed digital broadcast signal DBD.

Returning to FIG. 4, the combination part 240 receives the processedanalog broadcast signal ABD from the analog broadcast processing part220A and the processed digital broadcast signal DBD from the digitalbroadcast processing part 230. And the combination part 240 performscombination of this processed analog broadcast signal ABD and thisprocessed digital broadcast signal DBD. The result of this combinationis sent to the DAC 145 as the processed broadcast signal BPD.

Although this feature is not shown in the figures, the signalcombination by the combination part 240 is performed under control bythe control unit 120A. For example, the control unit 120A determines theratio for combination on the basis of the level detection result DLD,and commands the combination part 240 to employ this combination ratiowhich has been determined.

Returning to FIG. 1, the DAC 145 receives the processed broadcast signalBPD, which is a digital signal. And the DAC 145 converts this processedbroadcast signal BPD into an analog signal. The result of thisconversion is sent to the audio volume adjustment unit 150 as a signalBPS.

The audio volume adjustment unit 150 is endowed with the function of aso called electronic volume control. This audio volume adjustment unit150 receives the signal BPS from the DAC 145. And the audio volumeadjustment unit 150 performs processing to amplify or to attenuate thesignal BPS, according to an audio volume adjustment setting VLC from thecontrol unit 120A. The result of this processing is sent to the poweramplifier 155 as a volume adjusted audio signal VCS.

The power amplifier 155 receives the volume adjusted audio signal VCSfrom the audio volume adjustment unit 150. And the power amplifier 155performs power amplification of the volume adjusted audio signal VCS.The result of this amplification is sent to the speaker 160 as an audiooutput signal AOS.

The speaker 160 receives the audio output signal AOS from the poweramplifier 155. And the speaker 160 reproduces and outputs audiocorresponding to the audio output signal AOS.

The actuation input unit 170 consists of a key section which is providedin the main body portion of the broadcast receiving device 100A, or of aremote input device which includes such a key section or the like. Here,a touch panel which is provided upon the display unit 180 may be used asthis key section provided to the main body portion. Moreover, instead ofa structure which includes a key section, a structure which inputs audiomay also be employed. The result of actuation input to the actuationinput unit 170 is sent to the control unit 120A as actuation input dataIPD.

The display unit 180 comprises: (i) a display device such as a liquidcrystal display panel, an organic EL (Electro Luminescence) panel, a PDP(Plasma Display Panel), or the like; and (ii) a display control circuitwhich displays an image upon that display device, according to imagedata IDT received from the control unit 120A. Actuation guidance and thestate of the broadcast receiving device 100A are displayed upon thisdisplay unit 180.

Returning to FIG. 1, as described above, the control unit 120A controlsthe overall operation of this broadcast receiving device 100A. As shownin FIG. 7, this control unit 120A comprises a processing management part121, a digital broadcast judgment part 122 which serves as a judgmentmeans and a digital broadcast scan means, and a tuning control part 123which serves as a tuning control means.

The processing management part 121 performs control of the operation ofthis broadcast receiving device 100A, according to operation commandsinputted to the actuation input unit 170. In other words, when it isreported from the actuation input unit 170 that a tuning command whichdesignates some specific station has been inputted, then the processingmanagement part 121 sends to the tuning control part 123 a tuningrequest CSR designating this specific station to be selected. Moreover,when it is reported from the actuation input unit 170 that an audiovolume setting has been inputted, then the processing management part121 sends to the audio volume adjustment unit 150 the audio volumeadjustment setting VLC which corresponds to the designated audio volume.Moreover, the processing management part 121 sends to the display unit180 image data IDT for displaying actuation guidance and/or the state ofthe broadcast receiving device 100A.

Furthermore, when it is reported that an input has arrived from theactuation input unit 170 to the effect that scanning is to be performedfor a channel upon which a hybrid broadcast including a digitalbroadcast is being performed, then the processing management part 121sends a digital broadcast scan command to the digital broadcast judgmentpart 122. Here, when it is reported that an input has arrived from theactuation input unit 170 to the effect that searching is to be performedin a scan direction for the closest hybrid broadcast channel to thechannel which is currently being listened to, then the processingmanagement part 122 sends a digital broadcast seek command SSK to thedigital broadcast judgment part 122. Moreover, when it is reported thatan input has arrived from the actuation input unit 170 to the effectthat information must be collected for all hybrid broadcast channels ina frequency range which is set in advance, then the processingmanagement part 122 sends an all range digital broadcast scan commandSSC to the digital broadcast judgment part 122.

It should be understood that, in this first embodiment, the processingmanagement part 121 sets a start channel and an end channel related toscanning, in the case of both the seek command SSK and the all rangescan command SSC. Moreover, after having issued a seek command SSK or anall range scan command SSC, until the scan operation by the digitalbroadcast judgment part 122 ends, the processing management part 121sets the audio volume to 0 (i.e. to the mute state) with the audiovolume adjustment setting VLC.

Upon receipt of a seek command SSK or an all range scan command SSC fromthe processing management part 121, the digital broadcast judgment part122 starts scanning for a digital broadcast. During this scanning for adigital broadcast, the digital broadcast judgment part 122 sequentiallysends to the tuning control part 123 tuning requests CSQ in whichchannels to be selected are designated. And, each time a channel isselected according to such a tuning request CSQ, the digital broadcastjudgment part 122 changes over the signal selection by the switch part222A, using a bandwidth selection command BWC.

While controlling this change over of signal selection, the digitalbroadcast judgment part 122 collects the value V_(W) of the leveldetection result DLD if the signal WBD is selected, and collects thevalue V_(N) of the level detection result DLD if the signal NBD has beenselected. And a judgment is made as to whether or not this is a channelupon which hybrid broadcasting is being performed, on the basis of theresult of this collection of the values V_(W) and V_(N).

When a digital broadcast scan operation ends, the digital broadcastjudgment part 122 reports this fact to the processing management part121 as a scan end report STP. Here, in the case of an end report for theseek command SSK, the digital broadcast judgment part 122 reports to theprocessing management part 121 information as to the hybrid broadcastchannel which is closest in the scan direction to the channel which iscurrently being listened to. Furthermore, in the case of an end reportfor the all range scan command SSC, the digital broadcast judgment part122 reports to the processing management part 121 information as to theentire hybrid broadcast channels which have been found in the entirefrequency range set in advance.

The tuning control part 123 receives these tuning requests CSR from theprocessing management part 121 and these tuning requests CSQ from thedigital broadcast judgment part 122. And, each time it receives a tuningrequest CSR or a tuning request CSQ, the tuning control part 123 sends atuning command CSL corresponding to this received tuning request to thetuner unit 130.

[Operation]

The operation of this broadcast receiving device 100A having a structureas described above will now be explained with particular attention beingpaid to search processing performed by the digital broadcast judgmentpart 122, for finding a digital broadcast in a hybrid broadcast in whichboth analog broadcasting and digital broadcasting are being performed.

<<Seek Operation>>

First, the processing to seek for a digital broadcast in a hybridbroadcast will be explained.

This seek processing starts by the processing management part 121, towhich it has been reported that an input has arrived from the actuationinput unit 170 to the effect that seeking should be performed in thescan direction for the hybrid broadcast channel closest to the channelwhich is currently being listened to, sending a seek command SSK to thedigital broadcast judgment part 122. It should be understood that, asdescribed above, it is arranged for a seek start channel and a seek endchannel to be designated in the above seek command SSK.

As shown in FIG. 8, in this seek processing S10, first, in a step S11,the digital broadcast judgment part 122 sends to the tuning control part123 a tuning request CSQ to the effect that the start channel is to beselected. Upon receipt of this tuning request CSQ, the tuning controlpart 123 sends to the tuner unit 130 a tuning command CSL correspondingto the start channel. As a result, a tuning signal IFS, which is theintermediate frequency signal corresponding to the start channel, isextracted by the tuner unit 130. And, after this tuning signal IFS hasbeen converted to digital form by the ADC 135, the digital tuning signalIFD which is the result of this conversion is supplied to thereproduction processing unit 140A.

Next, in a step S12, the digital broadcast judgment part 122 performsjudgment processing for a first adjacent channel condition, which is acapability for estimating whether the channel which has been tunedincludes only a digital broadcast component. In this judgment processingfor the first adjacent channel condition of the step S12, as shown inFIG. 9, first, in a step S21, the digital broadcast judgment part 122collects the values V_(W) and V_(N).

When collecting these values V_(W) and V_(N), the digital broadcastjudgment part 122 first sends a bandwidth control command BWC to theswitch part 222A for the signal WBD to be selected. As a result, thesignal level V_(W) of the signal WBD is detected by the S-meter functionof the wave detection part 223A, and is reported to the digitalbroadcast judgment part 122 as the level detection result DLD. This isthe manner in which the digital broadcast judgment part 122 acquires thereported value V_(W).

Next, the digital broadcast judgment part 122 sends a bandwidth controlcommand BWC to the switch part 222A for the signal NBD to be selected.As a result, the signal level V_(N) of the signal NBD is detected by theS-meter function of the wave detection part 223A, and is reported to thedigital broadcast judgment part 122 as the level detection result DLD.This is the manner in which the digital broadcast judgment part 122acquires the reported value V_(N).

When the collection of the values V_(W) and V_(N) in this manner hasbeen completed, the flow of control proceeds to a step S22. In this stepS22, by making a judgment as to whether or not the value V_(W) is largerthan some predetermined value V_(W1), the digital broadcast judgmentpart 122 makes a judgment as to whether or not it is possible to inferthat an analog broadcast component or a digital broadcast component ispresent in the bandwidth of the channel which is selected. If the resultof this judgment is negative (N in the step S22), then it is consideredthat the first adjacent channel condition is not satisfied, and the flowof control is transferred to a step S13. It should be understood thatthis predetermined value V_(W1) is determined in advance by experiment,simulation, experience, or the like.

If the result of the judgment in this step S22 is affirmative (Y in thestep S22), then the flow of control proceeds to a step S23. In this stepS23, by making a judgment as to whether or not the value (V_(N)/V_(W))is smaller than some predetermined value R₁, the digital broadcastjudgment part 122 makes a judgment as to whether or not it is possibleto infer that the signal component included in the bandwidth of thechannel which is selected is only a digital broadcast component. Itshould be understood that this predetermined value R₁ is determined inadvance by experiment, simulation, experience, or the like.

If the result of this judgment in the step S23 is negative (N in thestep S23), then it is considered that the first adjacent channelcondition is not satisfied, and the flow of control is transferred tothe step S13. On the other hand, if the result of this judgment in thestep S23 is affirmative (Y in the step S23), then it is considered thatthe first adjacent channel condition is satisfied, and the flow ofcontrol is transferred to a step S14.

Returning to FIG. 8, if in the step S12 it is judged that the firstadjacent channel condition is not satisfied (N in the step S12) and theflow of control is transferred to the step S13, and then tuningprocessing for the next channel is performed. For this tuning processingto the next channel of the step S13, as shown in FIG. 10, first, thedigital broadcast judgment part 122 makes a judgment as to whether ornot the currently selected channel is a different channel from the endchannel which was designated in the seek command SSK. If the result ofthis judgment is negative (N in the step S31), then, as a scan endreport STP, the digital broadcast judgment part 122 reports to theprocessing management part 121 the fact that no channel has been foundon which hybrid broadcasting is being performed, and then the processingof this step S10 terminates.

If the result of the judgment in the step S31 is affirmative (Y in thestep S31), then the flow of control proceeds to a step S32. In this stepS32, the digital broadcast judgment part 122 sends to the tuning controlpart 123 a tuning request CSQ to the effect that the next channel to thechannel which is currently selected should be selected. As a result, atuning command CSL corresponding to that next channel is sent to thetuner unit 130 by the tuning control part 123, and a digital tuningsignal IFD corresponding to that next channel is supplied to thereproduction processing unit 140A. Subsequently, the flow of controlreturns to the step S12.

Returning to FIG. 8, if in the step S12 it is judged that the firstadjacent channel condition is satisfied (Y in the step S12), then theflow of control is transferred to the step S14, in which tuningprocessing for the next channel is performed. For this tuning processingto the next channel of the step S14, as shown in FIG. 10, after tuningto the next channel, similar processing to that of the step S13described above is performed, except for the fact that the flow ofcontrol proceeds to a step S15.

Returning to FIG. 8, when tuning is performed in the step S14 to thenext channel and the flow of control proceeds to the step S15, then thedigital broadcast judgment part 122 performs judgment processing for acentral channel condition, i.e. whether or not it is possible to inferthat the channel which has been tuned to includes both an analogbroadcast component and also a digital broadcast component. In thisjudgment processing of the step S15 for this central channel condition,as shown in FIG. 11, first, in a step S41, in a similar manner to thecase in the step S21 described above, the digital broadcast judgmentpart 122 collects the values V_(W) and V_(N).

Next, in a step S42, by making a judgment as to whether or not the valueV_(W) is larger than some predetermined value V_(W2), the digitalbroadcast judgment part 122 makes a judgment as to whether or not it ispossible to infer that an analog broadcast signal component or a digitalbroadcast component is present in the bandwidth of the channel which isselected. If the result of this judgment is negative (N1 in the stepS42), then, along with it being considered that the center channelcondition is not satisfied, also it is considered that the abovedescribed first adjacent channel condition is not satisfied, and theflow of control is transferred to the step S13. It should be understoodthat this predetermined value V_(W2) is determined in advance byexperiment, simulation, experience, or the like.

If the result of the judgment in this step S42 is affirmative (Y in thestep S42), then the flow of control proceeds to a step S43. In this stepS43, by making a judgment as to whether or not the value (V_(N)/V_(W))is greater than or equal to some predetermined value R₂, the digitalbroadcast judgment part 122 makes a judgment as to whether or not it ispossible to infer that an analog broadcast component and a digitalbroadcast component are included in the bandwidth of the channel whichis selected. It should be understood that this predetermined value R₂ isdetermined in advance by experiment, simulation, experience, or thelike.

If the result of this judgment in the step S43 is negative (N2 in thestep S43), then it is considered that, although the central channelcondition is not satisfied, still the first adjacent channel conditionis satisfied, and the flow of control returns to the step S14. On theother hand, if the result of this judgment in the step S43 isaffirmative (Y in the step S43), then it is considered that the centralchannel condition is satisfied, and the flow of control is transferredto a step S16.

Returning to FIG. 8, in the step S15, if it is judged that the centralchannel condition is satisfied (Y in the step S15), and then the flow ofcontrol is transferred to the step S16, in which processing for tuningto the next channel is performed. For this tuning processing to the nextchannel of the step S16, as shown in FIG. 10, after tuning to the nextchannel, similar processing to that of the step S13 described above isperformed, except for the fact that the flow of control proceeds to thestep S17.

Returning to FIG. 8, in the step S16 tuning to the next channel isperformed, and then the flow of control proceeds to a step S17, in whichthe digital broadcast judgment part 122 performs judgment processing ofthe second adjacent channel condition as to whether or not it ispossible to infer that only a digital broadcast component is included inthe bandwidth of the channel which is tuned. In this judgment processingof the step S17 for the second adjacent channel condition, as shown inFIG. 12, first, in a step S51, in a similar manner to the case in thestep S21 described above, the digital broadcast judgment part 122collects the values V_(W) and V_(N).

Next, in the step S52, by making a judgment as to whether or not thevalue V_(W) is larger than some predetermined value V_(W1), the digitalbroadcast judgment part 122 makes a judgment as to whether or not it ispossible to infer that an analog broadcast signal component or a digitalbroadcast component is present in the bandwidth of the channel which isselected. If the result of this judgment is negative (N in the stepS52), then it is considered that the second adjacent channel conditionis not satisfied, and the flow of control is transferred to the stepS13.

If the result of the judgment in this step S52 is affirmative (Y in thestep S52), then the flow of control proceeds to a step S53. In this stepS53, by making a judgment as to whether or not the value (V_(N)/V_(W))is smaller than some predetermined value R₁, the digital broadcastjudgment part 122 makes a judgment as to whether or not it is possibleto infer that the signal component included in the bandwidth of thechannel which is selected is a digital broadcast component.

If the result of this judgment in the step S53 is negative (N in thestep S53), then it is considered that the second adjacent channelcondition is not satisfied, and the flow of control is transferred tothe step S13. On the other hand, if the result of this judgment in thestep S53 is affirmative (Y in the step S53), then it is considered thatthe second adjacent channel condition is satisfied, and the flow ofcontrol is transferred to a step S18.

Returning to FIG. 8, in the step S18, the digital broadcast judgmentpart 122 reports to the processing management part 121, as a scan endreport STP, information about the channel for which, in the step S15described above, it was judged that the central channel condition wassatisfied, in other words frequency information for the central channelwhich corresponds to the channel upon which hybrid broadcasting is beingperformed. Then, the seek processing of this step S10 terminates.

Upon receipt of this information about the central channel which hasbeen found by the seek processing, the processing management part 121sends to the tuning control part 123 a tuning request CSR to the effectthat this central channel is to be selected. And, upon receipt of thistuning request CSR, the tuning control part 123 sends to the tuner unit130 a tuning command CSL corresponding to this central channel. As aresult, a tuning signal IFS, which is the intermediate frequency signalcorresponding to the start channel, is extracted by the tuner unit 130.And, after this tuning signal IFS has been converted to digital form bythe ADC 135, the digital tuning signal IFD which is the result of thisconversion is supplied to the reproduction processing unit 140A. Andsignal processing is sequentially performed by the reproductionprocessing unit 140A, the DAC 145, the audio volume adjustment unit 150,and the power amplifier 155, and thereby the audio of the hybridbroadcast which has been found is reproduced and outputted from thespeaker 160.

<<All Range Scan Operation>>

Next, the all range scan processing for digital broadcasts in hybridbroadcasts will be explained.

This all range scan processing is started by the processing managementpart 121, to which it has been reported that information about hybridbroadcast channels is to be collected for an entire range of frequenciesset in advance, sending an all range scan command SSC to the digitalbroadcast judgment part 122. It should be understood that, as describedabove, a start channel for scanning and an end channel are designated bythis all range scan command SSC.

As shown in FIG. 13, in this all range scan processing S60, processingof steps S11 through S17 is executed in a similar manner to the case ofthe seek processing described above. It should be understood that, inthe steps S13, S14, and S16, when it has been judged that the all rangescan processing S60 should end, information related to all of the hybridbroadcasts which have been found by this all range scan is reported tothe processing management part 121 as a scan end report STP; and in thisregard, this processing differs from the seek processing S10.

Furthermore, in this all range scan processing S60, if in the step S17it has been judged that the second adjacent channel condition issatisfied, then in a step S61, instead of the step S18 in the case ofthe seek processing S10, it is arranged for information about thecentral channel of the hybrid broadcast which has been found is storedin the digital broadcast judgment part 122. And, after the processing ofthe step S61, the flow of control returns to the step S13.

Upon receipt of this information about the channels which are beingutilized for hybrid broadcast found by the all range scan processing,the processing management part 121 applies this information for displayof actuation guidance or the like. As a result, the convenience for theuser is enhanced.

As has been explained above, in this first embodiment, the search forhybrid broadcasts according to the IBOC system is conducted by, whilesequentially changing the selected channel, collecting the signal levelvalue V_(W) of the signal extracted on wide band, i.e. of the so calledWBD signal, which is a signal of bandwidth appropriate for reproductionof an analog broadcast, and the signal level value V_(N) of the signalNBD extracted on narrow band, which is a signal of bandwidth around ΔFfor which, in the case of the IBOC system, there is a possibility thatneither a digital broadcast component nor an analog broadcast componentis present. And the search for channels upon which hybrid broadcastingis being performed is conducted by deciding, only on the basis of thesesignal level values V_(W) and V_(N), for three consecutive channels,whether or not the first adjacent channel condition, the central channelcondition, and the second adjacent channel condition are sequentiallysatisfied.

Accordingly, since it is possible to perform this operation withoutanalyzing the received contents and checking whether a digital broadcastis included therein, it is possible, when receiving a radio broadcastaccording to the IBOC system, promptly to decide whether or not adigital broadcast is included therein.

The Second Embodiment

Next, the second embodiment of the present invention will be explainedwith reference principally to FIGS. 14 through 16.

<Structure>

The schematic structure of a broadcast receiving device 100B accordingto a second embodiment is shown as a block diagram in FIG. 14. It shouldbe understood that, in a similar manner to the broadcast receivingdevice 100A of the first embodiment, this broadcast receiving device100B also is a broadcast receiving device which is capable of receivingand reproducing amplitude modulated radio broadcasts according to theIBOC system.

As shown in FIG. 14, as compared to the broadcast receiving device 100Adescribed above, this broadcast receiving device 100B only differs inthat it comprises a control unit 120B instead of the control unit 120A,and in that it comprises a reproduction processing unit 140B instead ofthe reproduction processing unit 140A. In the following, the explanationwill principally focus upon these points of difference.

As compared to the control unit 120A, this control unit 120B onlydiffers in that it has an analog input port at which is inputted thelevel detection signal DLS, which is reported as an analog signal. Atthis analog input port, the level detection signal DLS is converted todigital, and then it is supplied to the interior of the control unit120B.

The reproduction processing unit 140B receives the tuning signal IFSfrom the tuner unit 130 and the digital tuning signal IFD from the ADC135. And the reproduction processing unit 140B generates the processedbroadcast signal BPD, similar to the case with the reproductionprocessing unit 140A. As shown in FIG. 15, as compared to thereproduction processing unit 140A, this reproduction processing unit140B differs in that, instead of the analog broadcast processing part220A, it comprises an analog broadcast processing part 220B, and in thatit is additionally provided with an ADC 229.

The analog broadcast processing part 220B performs processing of thetuning signal IFS from the tuner unit 130, which is an analog signal,and generates a processed analog broadcast signal ABS, which is ananalog signal. As compared with the analog broadcast processing part220A, as shown in FIG. 16, this analog broadcast processing part 220Bdiffers in that, instead of the elements 221A through 225A which aredigital signal processing elements, it comprises elements 221B through225B which are analog signal processing elements. These elements 221Bthrough 225B perform the same processing as the elements 221A through225A, by analog processing. Here, the signal level detected by the wavedetection part 223B by the S-meter function is reported to the controlunit 120B as the level detection signal DLS.

Returning to FIG. 15, the processed analog broadcast signal ABS whichhas been generated by the analog broadcast processing part 220B is sentto the ADC 229. Upon receipt of this processed analog broadcast signalABS, the ADC 229 converts this processed analog broadcast signal ABSdigitally, and generates therefrom a processed analog broadcast signalABD, which is a digital signal. The processed analog broadcast signalABD which has been generated in this manner is sent to the combinationpart 240.

<Operation>

The broadcast receiving device 100B having the structure as describedabove operates in a similar manner to the broadcast receiving device100A of the first embodiment, except for the fact that, in thereproduction processing unit 140B, analog broadcast processing isperformed by the analog broadcast processing part 220B as analog signalprocessing, and the result is converted to digital. And, when searchingfor a digital broadcast in a hybrid broadcast, in a similar manner tothe broadcast receiving device 100A, the processing of FIGS. 8 through13 described above is executed by the digital broadcast judgment part122 of the control unit 120B.

As has been explained above, in this second embodiment, in a similarmanner to the first embodiment described above, searching for a hybridbroadcast according to the IBOC system is performed while sequentiallychanging the selected channel, by collecting the signal level valueV_(W) of the signal WBS extracted on wide band, which is a signal ofbandwidth suitable for reproduction of an analog broadcast, and thesignal level value V_(N) of the signal NBS extracted on narrow band,which is a signal of bandwidth around ΔF for which, in the case of theIBOC system, there is a possibility that neither a digital broadcastcomponent nor an analog broadcast component is present. And the searchfor channels upon which hybrid broadcasting is being performed isconducted by deciding, only on the basis of these signal level valuesV_(W) and V_(N), for three consecutive channels, whether or not thefirst adjacent channel condition, the central channel condition, and thesecond adjacent channel condition are sequentially satisfied.

Thus according to this second embodiment, in a similar manner to thecase for the first embodiment, since it is possible to perform thisoperation without analyzing the received contents and checking whether adigital broadcast is included therein, it is possible, when receiving aradio broadcast according to the IBOC system, promptly to decide whetheror not a digital broadcast is included therein.

Modification of the Embodiment

The present invention should not be considered as being limited to theembodiments described above; many variations may be implemented.

For example, in the first and second embodiment described above, it isarranged to detect the signal levels of the signal WBD (WBS) and thesignal NBD (NBS) by employing the S-meter function of the wave detectionpart 223A (223B). By contrast, it would also be possible to provide asignal level detection part which detects the signal levels of thesignal WBD (WBS) and the signal NBD (NBS), separately from the wavedetection part 223A (223B).

In this case, it would be possible to provide a single signal leveldetection part which is utilized for detecting the signal levels of thesignal WBD (WBS) and the signal NBD (NBS), and to change over the signalwhich is the subject of detection by a switch, in a similar manner tothe cases with the first and the second embodiments. Moreover, it wouldalso be possible to provide a dedicated signal level detection part foreach of the signals WBD (WBS) and NBD (NBS), and to perform detection ofboth of the signal levels in parallel.

Furthermore while, in the first and second embodiment described above,the explanation was made under the supposition that the predeterminedvalue V_(W1) and the predetermined value V_(W2) were different values,it would also be possible for the predetermined value V_(W1) and thepredetermined value V_(W2) to have the same value.

Furthermore while, in the first and second embodiment described above,the explanation was made under the supposition that the predeterminedvalue R₁ and the predetermined value R₂ were different values, it wouldalso be possible for the predetermined value R₁ and the predeterminedvalue R₂ to have the same value.

Furthermore while, in the first and second embodiment described above,it was supposed that the scan direction for searching for a hybridbroadcast was determined in advance, it would also be possible toarrange for the user to be able to designate this scan direction byactuation input, in particular during the seek processing.

Furthermore, in the first and second embodiment described above, thecondition for searching for a hybrid broadcast was taken as being thatthree consecutive channels satisfied the first adjacent channelcondition, the central channel condition, and the second adjacentchannel condition in order. By contrast, depending upon the receptionenvironment such as a radio wave environment and the like, it would alsobe possible to take the condition for searching for a hybrid broadcastas being that two consecutive channels satisfy the first adjacentchannel condition and the central channel condition in order, or satisfythe central channel condition and the second adjacent channel conditionin order.

It should be understood that it would also be acceptable to arrange toconstitute a portion or the entirety of the control units and thereproduction processing units of the first and the second embodimentsdescribed above as a computer, which serves as a calculation means, andwhich comprises a central processing device (CPU: Central ProcessingUnit), a DSP (Digital Signal Processor), a dedicated read out memory(ROM: Read Only Memory), a random access memory (RAM: Random AccessMemory), and so on; and, by executing a program which is prepared inadvance on that computer, to execute digital processing for the abovedescribed first and second embodiments. This program may be recordedupon a recording medium which can be read by a computer, such as a harddisk, a CD-ROM, a DVD, or the like, and may be read out by the abovecomputer from this recording medium and executed. Furthermore, it wouldalso be acceptable to arrange for this program to be acquired in thestate of being recorded upon a transportable recording medium such as aCD-ROM, a DVD, or the like; or it would also be acceptable to arrangefor the program to be acquired in a distribution format via a networksuch as the internet or the like.

1. A broadcast receiving device, characterized by comprising: a tunerpart configures to, according to a tuning command, convert a signal in asignal from a signal source, on a frequency band corresponding to saidtuning command, to an intermediate frequency signal, which is a signalon an intermediate frequency band whose center frequency is apredetermined frequency; a first filter part configures to, if saidpredetermined frequency corresponds to a frequency of a carrier wave ofan analog radio broadcast according to the amplitude modulation method,take said predetermined frequency as a center frequency, and selectsfrom said intermediate frequency signal and passes through a signal on afirst frequency band which is appropriate for reproducing broadcastcontents from said analog radio broadcast; a second filter partconfigures to take said predetermined frequency as a center frequency,and select from said intermediate frequency signal and passes through asignal on a second frequency band whose bandwidth is narrower than saidfirst frequency band; a first detection part configures to detect afirst power level, which is the power level of the signal passed throughsaid first filter part; a second detection part configures to detect asecond power level, which is the power level of the signal passedthrough said second filter part; a tuning control part configures toissue said tuning command to said tuner part; and a judgment partconfigures to, on the basis of said first power level and said secondpower level obtained corresponding to a tuning command in which aspecific channel is designated, and said first power level and saidsecond power level obtained corresponding to a tuning command in whichat least one adjacent channel to said specific channel is designated,make a judgment as to whether or not a digital radio broadcast whichtakes the center frequency of said specific channel as its centerfrequency is being performed according to an in-band-on-channel method.2. A broadcast receiving device according to claim 1, characterized inthat said judgment part configures to judge that a digital radiobroadcast which takes the center frequency of said specific channel asits center frequency is being performed according to the in-bandon-channel method, if a judgment condition is satisfied which includes:a first condition that, when said specific channel is designated by saidtuning command, said first power level is greater than or equal to afirst predetermined power level and also said second power level is lessthan or equal to a second predetermined power level; and a secondcondition that, when one of said adjacent channels is designated by saidtuning command, said first power level is greater than or equal to athird predetermined power level and also the ratio of said second powerlevel to said first power level is less than or equal to a predeterminedvalue.
 3. A broadcast receiving device according to claim 2,characterized in that, in said judgment condition there is furtherincluded a third condition, that when another said adjacent channel isdesignated by said tuning command, said first power level is greaterthan or equal to the third predetermined power level and also the ratioof said second power level to said first power level is less than orequal to a predetermined value.
 4. A broadcast receiving deviceaccording to claim 3, characterized by further comprising a switch partconfigures to, according to a changeover command, supply saidintermediate frequency signal to either said first filter part or saidsecond filter part; and in that said judgment part issues saidchangeover command to said switch part.
 5. A broadcast receiving deviceaccording to claim 3, characterized by further comprising a digitalbroadcast scan part configures to, for a plurality of radio broadcastchannels which are determined as being arranged at predeterminedfrequency intervals, control said tuning control part so as to issuesaid tuning command in order of frequency.
 6. A broadcast receivingdevice according to claim 2, characterized by further comprising aswitch part configures to, according to a changeover command, supplysaid intermediate frequency signal to either said first filter part orsaid second filter part; and in that said judgment part issues saidchangeover command to said switch part.
 7. A broadcast receiving deviceaccording to claim 2, characterized by further comprising a digitalbroadcast scan part configures to, for a plurality of radio broadcastchannels which are determined as being arranged at predeterminedfrequency intervals, control said tuning control part so as to issuesaid tuning command in order of frequency.
 8. A broadcast receivingdevice according to claim 1, characterized by further comprising aswitch part configures to, according to a changeover command, supplysaid intermediate frequency signal to either said first filter part orsaid second filter part; and in that said judgment part issues saidchangeover command to said switch part.
 9. A broadcast receiving deviceaccording to claim 8, characterized by further comprising a digitalbroadcast scan part configures to, for a plurality of radio broadcastchannels which are determined as being arranged at predeterminedfrequency intervals, control said tuning control part so as to issuesaid tuning command in order of frequency.
 10. A broadcast receivingdevice according to claim 1, characterized by further comprising adigital broadcast scan part configures to, for a plurality of radiobroadcast channels which are determined as being arranged atpredetermined frequency intervals, control said tuning control part soas to issue said tuning command in order of frequency.
 11. A broadcastidentification method, characterized by comprising: a tuning process of,according to a tuning command, converting a signal in a signal from asignal source, on a frequency band corresponding to said tuning command,to an intermediate frequency signal, which is a signal on anintermediate frequency band whose center frequency is a predeterminedfrequency; a first detection process of, if said predetermined frequencycorresponds to a frequency of a carrier wave of an analog radiobroadcast according to the amplitude modulation method, taking saidpredetermined frequency as a center frequency, extracting from saidintermediate frequency signal a signal on a first frequency band whichis appropriate for reproducing broadcast contents from said analog radiobroadcast, and detecting the power level of this extracted signal; asecond detection process of taking said predetermined frequency as acenter frequency, extracting from said intermediate frequency signal asignal on a second frequency band whose bandwidth is narrower than saidfirst frequency band, and detecting the power level of this extractedsignal; and a judgment process of, on the basis of the result ofdetection by said first detection process and the result of detection bysaid second process when a specific channel has been designated by saidtuning command, and the result of detection by said first detectionprocess and the result of detection by said second process when at leastone adjacent channel to said specific channel is designated by saidtuning command, making a judgment as to whether or not a digital radiobroadcast which takes the center frequency of said specific channel asits center frequency is being performed according to thein-band-on-channel method.
 12. A broadcast identification program,characterized in that it causes a calculation part to execute abroadcast identification method according to claim
 11. 13. A recordingmedium, characterized in that a broadcast identification programaccording to claim 12 is recorded thereupon, and can be read in by acalculation part.